What is a cavity wall tie?
Cavity walls are made of two skins of brickwork/blockwork with a gap between. Single skin brickwork can only be built up to 1-2 metres before it becomes too unstable, therefore the two layers are attached to each other with ties, which come in a variety of sizes and shapes. Before 1945 there were no standards so the quality of these ties varied dramatically.
What is wall tie corrosion and failure?
In early cavity brick designs the ties were larger metal structures without zinc coating. Overtime when these ties get wet they rust, and corrode. This causes the ties to get bigger and expand the mortar joints. As the joints expand the ties become loose, and eventually fail.
What are some main symptoms?
- Horizontal cracks every 4-5 brick courses is a classic sign of corrosion. When the ties corrode they expand in size, this expands the mortar joints, creating this tell tale sign.
- Bulging of the brickwork is another symptom. This is caused by the outer skin of brickwork peeling/falling away from the inner skin of wall.
- When the mortar joints expend this can cause the gable end walls to lift causing a lift at the end of the roof ridges. This is another symptom to look out for.
What can you do to resolve cavity wall tie failure?
When Crookshank & Co undertake a survey on your prospective house purchase, we will be looking for any signs of wall tie failure and corrosion. The next step in the process is to have the wall ties inspected. This is done with a Cavity Wall Tie survey. Usually this will involve drilling holes into the cavity to use an endoscope camera to view the condition of the ties.
By taking early action after your Homebuyer survey you can undertake action to prevent any further movement and secure the walls. This work will usually involve installing new steel ties, occasionally the original ties will be removed. This should only be done by an appropriately qualified contractor. Upon completion of this work they should provide you with a long term guarantee.
Find out more about Cavity Wall Ties below
To find out more at the Property Care Association Click Here.
To find out more about possible solutions click here.
A brief overview of cavity wall tie failure.
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